JPH10138708A - Pneumatic radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress or prevent the generation of trouble such as separation at the place where a side edge rubber and a side rubber are joined together. SOLUTION: The pneumatic tire is provided with a bead core 1, a carcass-ply 2, a flexible side rubber 4 arranged outside the carcass-ply 2 in the tire-axis direction, a top tread 5 arranged radially in the outer side of a crown part, and a pair of right and left side edge rubbers 6 which are arranged on both sides of the top tread 5 and which are of the same quality as the side rubber 4. In this case, a narrow strip 7 adjacent to the outer part of a shoulder part of the carcass-ply 2, is arranged in the circumferential direction of the tire, and the narrow strip 7 is reinforced by radial fiber cords. The narrow strip 7 is extended upward and downward in the radial direction around a boundary line in the outer side of the tire between the side edge rubber 6 and the side rubber 4, and the lower end edge of the narrow strip 7 in the radial direction is positioned above a position of maximum width of the tire.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic radial
Particularly related to tires, in particular, a bead core provided on a pair of left and right bead portions, and a radial cord extending from one bead portion to the other bead portion and wound around the bead core and moored at the bead portion. A carcass ply comprising a layer, a belt disposed radially outward of a crown portion of the carcass ply, a side rubber having high bending resistance disposed radially outward of the carcass ply in a tire axial direction, and the belt And a top tread with high wear resistance disposed radially outward of the crown portion of the pneumatic radial tire.

[0002]

2. Description of the Related Art Radial tires are generally manufactured by
For the reasons as described in US Pat. No. 18790, two-stage molding, that is, a first molding step of attaching a part of a tire member such as a radial carcass on a cylindrical former, and then expanding in a toroidal shape. It is manufactured through a second molding step of attaching the remaining tire member such as a belt. This conventional radial tire is manufactured in three types, namely, the oldest side tipping method (hereinafter referred to as A).
Type), an improved side backing system (hereinafter referred to as a B type), and a top D / T or mini skirt system (hereinafter referred to as a C type) having both advantages.

In the A type, as described in JP-B-49-18790, after a radial carcass is stuck on a cylindrical former, some tire members such as side rubber (inner liner, bead core, The stiffener, flipper, chafer, etc.) are manufactured through a first molding process, followed by a second molding process in which the remaining tire members such as belts are attached in a state of being expanded in a toroidal shape. However, cracks may occur at the joint between the tread rubber and the side rubber, leading to a separation failure.

In the B type, as described in JP-B-49-18790, molding is performed in the same manner as in the A type, but in the first molding step, a polyethylene sheet is inserted below the crown of the side rubber. Beforehand, the side rubber is caused together with the polyethylene sheet in the second molding step, and after the tread rubber is applied, the side rubber is applied. Type A is referred to as a side tipping method because the side rubber is attached to the tip of the tread rubber, while type B is referred to as a side trailing method because the side rubber is attached later. In the case of the B type, defects such as the A type were removed, and cracks were generated, thereby preventing the separation failure. However, the productivity was clearly inferior.

The C type is the invention itself described in JP-B-49-18790, and is the most popular method of manufacturing radial tires at present. The C type is molded in the same manner as the A type, except that the same side edge rubber as the side rubber is integrally formed on both sides of the tread rubber in advance. Preventing separation failures, making it the most popular method of manufacturing radial tires today. "Tread" of tread rubber means tread,
Refers to the rubber layer provided outside the crown of the tire,
It is often referred to as top rubber to distinguish it from side rubber, which is a rubber layer provided outside the side portion of the tire. The C type is often referred to as a top D / T method since a side edge rubber of the same quality as the side rubber is extruded and formed integrally with the dual rubber on both sides of the top rubber in advance. In addition,
It is also called a mini skirt system because of the appearance of the side edge rubber of the same quality as the rubber. Details of the conventional technology of A type, B type and C type are described in JP-B-49-18790.
See

[0006]

Prior art type C, as described above, is currently the most popular method of making radial tires, but is usually seen when the tire is used under extreme conditions. There was no phenomenon.
That is, cracks or cracks occur at the joint between the side rubber and the side skirt rubber (mini skirt portion) integrally formed on both sides of the tread rubber, resulting in a problem of separation failure. Since this side edge rubber is of the same quality as the side rubber, such a phenomenon was not normally observed.However, when the conditions of use of the tire became severe, the joint portion between the side edge rubber and the side rubber was formed. It was found that the generated strain was relatively large and cracks occurred. It has been found that when the ratio between the tire height and the tire width (hereinafter, referred to as H / S) becomes small and an ultra-flat pneumatic radial tire is formed, this phenomenon is remarkably apt to appear. In order to avoid this problem, it is sufficient to return to the B type of the prior art, but since the productivity is clearly inferior, it is an easy workaround, but it is difficult to adopt from the viewpoint of commercial production. . Furthermore, in the case of an ultra-flat pneumatic radial tire having an H / S of 55% or less, the operation of causing the side rubber together with the polyethylene sheet in the second molding step, in combination with the narrow side rubber width, is more than the ordinary tire. Effort is required, and from this point it is not permissible to return to the B type easily.

An object of the present invention is to provide a pneumatic radial tire which solves the above-mentioned disadvantages of the prior art and suppresses or prevents the occurrence of separation failure at the joint between the side edge rubber and the side rubber. That is.

[0008]

In order to achieve the above object, a pneumatic radial tire according to the present invention comprises a bead core provided on a pair of left and right bead portions, and a bead portion from one bead portion to the other bead portion. A carcass ply consisting of a radial cord layer wound around the bead core and moored to the bead portion; a belt disposed radially outside the crown portion of the carcass ply;
Bend-resistant side rubber disposed outside the ply in the tire axial direction, wear-resistant top tread disposed radially outside the crown portion of the belt, and disposed on both sides of the top tread The side
In a pneumatic tire provided with a pair of left and right side edge rubbers of the same quality as rubber, (1) a narrow strip extending annularly in a tire circumferential direction is disposed adjacent to an outer side of a shoulder portion of the carcass ply; 2) the narrow strip is reinforced with radially extending fiber cords; and (3) the narrow strip is radially above and below the tire outer boundary line between the side rubber and the side rubber. (4) The pneumatic radial tire characterized in that the radially lower edge of the narrow strip is located above the maximum width of the tire.

In order to achieve the above object, in the pneumatic radial tire of the present invention, the radially upper edge of the narrow strip may be interposed between the carcass ply and the belt. preferable.

[0010] The pneumatic radial tire of the present invention has the above-described structure, and particularly, extends in the tire circumferential direction annularly adjacent to the outside of the shoulder portion of the carcass ply.
A narrow strip reinforced with a fiber cord extending in the radial direction is disposed, and the narrow strip extends radially upward and downward with respect to the tire outer boundary line between the side rubber and the side rubber. The surface tensile strain generated in the vicinity of the tire outer boundary line between the side rubber and the side rubber is reduced, and it becomes possible to suppress or prevent the separation failure that tends to occur at the boundary line. Further, in the pneumatic radial tire of the present invention, as described above, the radially lower edge of the narrow strip is located above the maximum width of the tire. Since the radially upper edge of the strip is interposed between the carcass ply and the belt, the reinforcing effect is greater than when the strip is free.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a pneumatic radial tire according to an embodiment of the present invention and a conventional pneumatic radial tire will be described with reference to the drawings. All tire sizes are 205 / 60R15.

FIG. 1 is a schematic partial sectional view of a pneumatic radial tire according to an embodiment of the present invention. As shown, the pneumatic radial tire according to the embodiment of the present invention has a pair of right and left bead portions. A bead core 1 provided; a carcass ply 2 comprising a radial cord layer extending from one bead portion to the other bead portion and wound around the bead core 1 and moored to the bead portion; 2
Belt 3 arranged radially outward of the crown portion of
A side rubber 4 having high bending resistance disposed outside the carcass ply 2 in the tire axial direction; a top tread 5 having high wear resistance disposed outside the crown portion of the belt 3 in the radial direction; This is a pneumatic radial tire provided with edge rubber 6. A pneumatic radial tire according to an embodiment of the present invention has a carcass ply 2 as shown in the figure.
A narrow strip 7 extending annularly in the circumferential direction of the tire is disposed adjacent to the outer side of the shoulder portion, and the narrow strip 7 is reinforced by a fiber cord extending in the radial direction. The narrow strip 7 extends radially upward and downward with respect to a boundary line L between the side rubber 4 and the side rubber 6 on the outer side of the tire. It is located above the maximum width. The radially upper edge of the narrow strip 7 is
It is interposed between the carcass ply 2 and the belt 3.

The conventional pneumatic radial tire has substantially the same structure as the pneumatic radial tire of the above embodiment, except that it does not include the narrow strip 7 described above.

When the surface distortion of the sidewall was measured for the pneumatic radial tire of the above embodiment and the conventional pneumatic radial tire, the conventional pneumatic radial tire showed a tensile strain of about 10%. In contrast, the pneumatic radial tire of the above example had a tensile strain of about 5%. Further, the pneumatic radial tire of the above-described embodiment and the pneumatic radial tire of the conventional example described above have side edge rubbers (mini skirts).
An evaluation test was conducted on the separation generated at the joint between the rubber part) and the side rubber. The running distance before the separation occurred on the drum tester was about 15,000 km for the conventional pneumatic radial tire, whereas the running distance for the pneumatic radial tire of the above embodiment was about 35,000 km.
It was 000 km.

[0015]

According to the above evaluation results, the pneumatic radial tire according to the embodiment of the present invention is compared with the pneumatic radial tire according to the prior art in that the side edge rubber (mini skirt portion) and the side tires are different. It can be seen that the separation resistance at the joint with the rubber is excellent.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a pneumatic radial tire according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bead core 2 Carcass ply 3 Belt 4 Side rubber 5 Top tread 6 Side rubber 7 Narrow strip L Boundary line

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI B60C 9/22 B60C 9/22 D

Claims (2)

[Claims] 1. A bead core provided on a pair of left and right bead portions, and a radial cord layer extending from one bead portion to the other bead portion, wound around the bead core and moored to the bead portion. A carcass ply, a belt disposed radially outward of a crown portion of the carcass ply, a flex-resistant side rubber disposed radially outside of the carcass ply in a tire axial direction, and a crown of the belt. (1) A pneumatic tire comprising: a wear-resistant top tread disposed radially outward in a part radial direction; and side edge rubbers of the same quality as side rubber disposed on both sides of the top tread. A narrow strip extending annularly in the circumferential direction of the tire is disposed adjacent to the outside of the shoulder portion of the carcass ply, and (2) the narrow strip extends in the radial direction. (3) reinforced with vibrating fiber cord
The narrow strip extends radially upward and downward across a tire outer boundary line between the side edge rubber and the side rubber, and (4) a radially lower edge of the narrow strip is larger than a tire maximum width. A pneumatic radial tire, which is located above. 2. The pneumatic radial tire according to claim 1, wherein an upper radial edge of the narrow strip is interposed between the carcass ply and the belt.